Background

To verify the criteria for human T-lymphotropic virus (HTLV) seropositivity in Western blot (WB) proposed by the Retrovirus Study Group of the French Society of Blood Transfusion, 186 blood donations that were repeatably reactive in HTLV enzyme-linked immunosorbent assay, selected according to their WB pattern, were tested by polymerase chain reaction (PCR) and radioimmunoprecipitation assay (RIPA).

Study Design and Methods

In two commercially available WBs, 12 samples were confirmed as positive (rgp21p19+p24) and 174 were interpreted as indeterminate.

The primer pairs used for the PCR allowed the amplification of type I (HTLV-I) or type II (HTLV-II) (or both) sequences.

The RIPA was performed with two 35S-labeled cell lines : HTLV-I infected HUT 102/B2 and HTLV-II-infected MoT.

Results

Of the 12 positive samples, 11 were classified as HTLV-I-positive and one as HTLV-II-positive.

Among the 174 indeterminate samples, three (WB pattern : rgp21+p19+p24-) were HTLV-I positive in PCR (one of them was positive in RIPA also) ; the other 171 were HTLV negative.

Conclusion

In the study of a population in which 97 percent of HTLV infections are due to HTLV-I, these data support the three-protein criteria (rgp21, p19, and p24) for a positive blot reading.